Since You Asked: Why aren't there more solar panels on roofs?

Monday

Nov 20, 2017 at 12:01 AM

Since the Oregon Land Use Board of Appeals recently reversed Jackson County's approval of a 37,905-panel solar farm on a 90-acre property along Rossanley Drive just outside Medford because the solar array would have covered up prime ag land, I've been thinking about where else solar panels could be placed. Whenever I take off or land at the Medford airport (or any other city airport), I see dozens and dozens of large-box buildings, usually warehouse or big-box stores. These buildings have massive roofs. Why don't the owners of these buildings equip them with arrays of solar panels or rent their roofs to firms that will do it for them?

— Climate protector, Talent

We didn't speak with every commercial property owner in the region, Climate Protector, but we gather it's largely a matter of economics.

Buzz Thielmann, president of Oregon Energy Green, said a number of factors go into consideration of a solar installation.

To get state and federal tax credits, you have to prove that the installation will get at least 75 percent of the available sunlight, Thielmann said. The installation undergoes a rather bureaucratic sounding formula known as "Total Solar Resource Fraction." For instance, a north-facing roof probably wouldn't cut it.

"A lot of roofs aren't capable of this," Thielmann said.

Another issue is that most solar installations last 25 to 30 years. If a roof is 15 years old and is designed to last another 15 years, then putting a solar installation on top doesn't make economic sense. Thielmann said the roof and the solar installation would have to be pulled off in 15 years.

"One of the big questions we have is, 'What is the age of your roof?' "

A solar array installed on flat ground is a lot cheaper than one installed on a rooftop.

Solar fields typically cost about $2 a watt, Thielmann said. A rooftop installation is typically $3 to $3.25 a watt.

It's not that we don't have solar panels around the airport in Medford, C.P.

In fact, the Medford airport has solar panels in the parking area.

In the past, solar panels caused some glare that would have proved dangerous for airplanes at the airport.

"In the early days of solar, glare was a big issue," said Bern Case, the airport's director.

But improvements with the design and orientation of the solar panels has reduced the glare problem markedly, he said.

The airport already has solar panels that provide enough power for the parking lot area. Underground conduit is being installed in the expanded parking lot areas, which are under construction, so that solar panels can be installed in the future.

Case said the airport had been in discussions with a company that wanted to install more panels, but the deal didn't work out.

The airport also has a number of billboards that are also solar-powered.

Regarding big-box store roofs and solar panels, it would be up to the property owners to decide if they wanted arrays up top or in parking lots. Cascade Christian School, which is near the airport, has installed solar panels in its parking lot.

Properties near the airport should fill out a form that is submitted to the Federal Aviation Administration, which likes to know where solar panels are located, Case said.

— Send questions to “Since You Asked,” Mail Tribune Newsroom, P.O. Box 1108, Medford, OR 97501; by fax to 541-776-4376; or by email to youasked@mailtribune.com. We’re sorry, but the volume of questions received prevents us from answering all of them.